That's how i do it as well. I've tried just barely enough cotton up to way too much cotton and still get the same issue when the juice drops below the top of the wider part of the chamber/chimney. I think it has to do with vacuum pressure, today I tried drawing very slowly when it started to flood and that helped for a bit.That's how I wick the Xeta. Do a rough cut first then trim and fluff once the chimney is assembled. The cotton fluffs out to fill the squared off holes just fine if you take a little time and juice it well before it goes into the boro.